Your heart is an amazing organ. It continuously pumps oxygen and nutrient-rich blood throughout your body to sustain life. This fist-sized powerhouse beats 100,000 times per day, pumping five or six quarts of blood each minute, or about 2,000 gallons per day. There are three main types of blood vessels:

Arteries: begin with the aorta, the large artery leaving the heart. Arteries carry oxygen-rich blood away from the heart to all of the body's tissues. They branch several times, becoming smaller and smaller as they carry blood further from the heart and in to organs.

Capillaries: These are small, thin blood vessels that connect the arteries and the veins. Their thin walls allow oxygen nutrients, carbon dioxide and the other waste products to pass to and from each cell in our body.

Veins: These are blood vessels that take blood back to the heart; this blood lacks oxygen (oxygen-poor) and is rich in waste products that are to be excreted or removed from the body. Veins become larger and larger as they get closer to the heart. The superior vena cava is the large vein that brings blood from the head and arms to the heart, and the inferior vena cava brings blood from the abdomen and legs into the heart.

This vast system of blood vessels---arteries, veins, and capillaries- is over 60,000 miles long. That's long enough to go around the world more than twice!

Like all organs, your heart is made of tissue that requires a supply of oxygen and nutrients. Although its chambers are full of blood, the heart receives no nourishment from this blood. The heart receives its own supply of blood from a network of arteries called the coronary arteries.

Two major coronary arteries branch off from the aorta near the point where the aorta and the left ventricle meet:

Right coronary artery: Supplies the right atrium, right ventricle, and the bottom portion of the left ventricle and the back of the septum.

Left main coronary artery: supplies the left atrium, side and back of the left ventricle, the front and bottom of the left ventricle and the front of the septum.

These arteries and their branches supply all parts of the heart muscle with blood.

Coronary artery disease causes roughly 1.5 million heart attacks each year, and one-third of those suffering heart attacks die. Even more worrisome, 250,000 people with heart attacks will die before ever reaching the hospital.